This invention relates to a vibration reduction apparatus for an elevator which is capable of suppressing the vibrations of a car in an elevator.
FIG. 9 is a view showing the configuration of a known vibration reduction apparatus for an elevator disclosed in Japanese Patent Application Laid-Open No. 8-26624. An elevator cage 1 installed on a cage frame 2 engages a pair of rails 41, 42 on opposite sides of the cage frame 2 through guide devices 51-54 mounted thereon, so that an elevator is driven to move up and down along the rails 41, 42 by moving a wire rope (not shown) hanging the cage frame 2 in a vertical direction by means of a winch (not shown).
The guide devices 51-54 are arranged at four corners on opposite upper and lower sides of the cage frame 2. The guide devices 51-54 are provided with guide rollers 71-74 and actuators 81-84, respectively, which act as vibration reducers for suppressing vibrations of the car. The actuators 81-84 may be in the form of contactless actuators which are constituted by electromagnets, etc.
Information about the vibrations detected by acceleration sensors 61, 62 mounted on the cage frame 2 is sent to a controller 9 including control units 9a, 9b of the same configuration, where instruction values of control forces to be applied to the car for vibration reduction is calculated. The instruction values are sent to current amplifiers 93, from which driving currents are supplied to the actuators 81-84, respectively, based on the instruction values. At this time, the actuators 81-84 generate forces corresponding to horizontal vibrations of the car and apply then to the guide rails 41, 42 thereby to suppress transverse vibrations of the car.
Within the controller 9, acceleration signals are converted into corresponding speed signals by means of integrators 92 and then output to the current amplifiers 93 as instruction values. As a result, by applying to the car a force of the same magnitude and of the opposite direction with respect to the horizontal speed of the car, a damping force is added to the car, thus suppressing vibrations of the car.
Here, note that 91a-91d in the controller 9 designate amplifiers, and 94 designates a phase inverter. In addition, 31 and 32 designate vibration preventing rubber members disposed between the elevator cage 1 and the cage frame 2.
As the known vibration reduction apparatus for an elevator is constructed in the above-described manner, there arise the following problems. That is, drift noise having low frequencies contained in the signals of the acceleration sensors is increased or amplified by integrating the acceleration sensor signals in the controller, and a large low frequency error might be superposed on and hence contained in each instruction value. Thus, the current amplifiers for driving the actuators each require a large power supply capacity. In addition, when the car is temporarily stopped at a floor during operation of the elevator, the car might be caused to vibrate by the noise in the acceleration sensor outputs, thus resulting in deteriorated riding comfort.
The present invention is intended to obviate the above-mentioned problems, and to produce a vibration reduction apparatus for an elevator which is improved in vibration suppression.
The present invention resides in a vibration reduction apparatus for an elevator which includes an acceleration sensor for detecting vibrations of a car, a controller for calculating a force to be applied to the car based on a signal of the acceleration sensor, and an actuator for applying a force to the car in accordance with the calculation result of the controller. The vibration reduction apparatus for an elevator is characterized in that a dead band filter, which has a prescribed dead band region corresponding to a noise level of the acceleration sensor, and an integrator, which integrates the signal of the acceleration sensor after having passed through the dead band filter, are provided between the acceleration sensor and the controller.
In addition, the apparatus is characterized in that the dead band filter and the integrator are provided in the controller.
Moreover, the apparatus is characterized in that the dead band filter has a dead band region in a range between xc2x12.5 cm/s2.
Further, the apparatus is characterized in that the controller is provided with a high-pass filter disposed downstream of the integrator.
Furthermore, the apparatus is characterized in that the controller is provided with means for forcedly adjusting the signal after integrated to zero during the car is stopped at a floor.
Still further, the apparatus is characterized in that the acceleration sensor comprises an acceleration sensor having a semiconductor built therein, and the dead band filter has a dead band region in a range between xc2x16 cm/s2.
Moreover, the apparatus is characterized in that the car is movable in a vertical direction along guide rails, with the actuator being arranged between the car and the guide rails.
In addition, the apparatus is characterized in that the car is provided with guide rollers for guiding the car along the guide rails so as to permit the car to move in the vertical direction therealong, with the actuator being arranged between the car and the guide rollers.
Moreover, the apparatus is characterized in that the car includes an elevator cage and a cage frame flexibly supporting the elevator cage, with the actuator being arranged between the elevator cage and the cage frame.
The present invention improves the vibration suppression performance in the vibration reduction apparatus for an elevator by adding the dead band filter or the high-pass filter in the controller which operates the actuator, for instance.